Growth Mechanism Research Articles

Evolution of Defects, Morphology, and Strain during FAMAPbI3 Perovskite Vacuum Deposition: Insights from In Situ Photoluminescence and X-ray Scattering.

At present, the power conversion efficiency of single-junction perovskite-based solar cells reaches over 26%. The further efficiency increase of perovskite-based optoelectronic devices is limited mainly by defects, causing the nonradiative recombination of charge carriers. To improve efficiency and ensure reproducible fabrication of high-quality layers, it is crucial to understand the perovskite nucleation and growth mechanism along with associated process control to reduce the defect density. In this study, we investigate the growth kinetics of a promising narrow bandgap perovskite, formamidinium methylammonium lead iodide (FAMAPbI3), for high-performance single-junction solar cells. The temporal evolution of structural and optoelectronic properties during FAMAPbI3 vacuum codeposition was inspected in real time by grazing-incidence wide-angle X-ray scattering and photoluminescence. Such a combination of analytical techniques unravels the evolution of intrinsic defect density and layer morphology correlated with lattice strain from the early stages of the perovskite deposition.

In situ mass spectrometric investigation to probe GeSn growth dynamics and mechanisms in the chemical vapor deposition processes

GeSn has attracted increasing attention due to its tunable bandgap from indirect to direct resulting in unique electronic and optoelectronic capabilities. Chemical vapor deposition (CVD) is well acknowledged as an advanced growth method for GeSn, demonstrating its capability with grown materials for infrared lasers and detector development. As an in situ diagnostics of the CVD process, a residual gas analyzer (RGA) could enable the detection of all gaseous species during growth, thus probing the growth dynamics and mechanism. Therefore, it is highly desirable but is lacking in the (Si)GeSn research community. This work utilized an RGA equipped with a specialized differential vacuum pumping system to analyze the mass spectra of the GeSn CVD precursors of SnCl4, GeH4, and their combination. The spectra of SnCl4 collected from gas samples at a standard base pressure of 0.3 Torr display consistent fragments with central mass-to-charge ratios (m/z) of 78, 120, 155, 225, and 260, corresponding to Sn+, SnCl2+, SnCl+, SnCl2+, SnCl3+, and SnCl4+, respectively. These profiles closely resemble those observed in the National Institute of Standards and Technology and Wiley and Matsumoto et al. The simultaneous introduction of SnCl4 and GeH4 at a combined pressure of several tens of Torr yields spectra, indicating a chemical reaction that produces GeCl4 at room temperature in the vacuum chamber and tubing. Utilizing Gaussian16 and ORCA codes, the ab initio and density functional thermochemistry computations were employed to predict potential essential reactions and validate the experimental findings.

The US-China race for technological centrality: A network perspective

This research analyzes the evolution of technological leadership in the global patents network, focusing on the roles of the US and China from 2001 to 2021. The US's central position in the network faces increasing challenges from China's economic and technological rise. This study goes beyond conventional approaches that analyze material capabilities by adopting a structural dynamic approach, which allows us to examine not only a country's centrality but also the mechanisms that lead a country to become central in the network. International technological influence is assessed through the global patents network by analyzing each country's position and growth mechanisms. The results show that, despite China's substantial growth in the network, the US remains the undisputed central power, benefiting from a growth mechanism that favors already central countries.

НАУЧНАЯ ШКОЛА ПРОФЕССОРА ПЕТРА ВАСИЛЬЕВИЧА СЕНИНА

The strategic task in the field of modern higher education is to develop the research potential of the university, to educate scientific staff. The effectiveness of this process depends on the successful functioning of scientific schools. In this regard, the research aimed at studying the experience of the author's scientific schools is relevant. (Research purpose) The research purpose is analyzing the concept and features of the scientific school as a form of personal growth and formation of researchers at the university using the example of research in the field of developing technologies for high-resource repair of machinery and technological equipment using metal coatings with specified functional properties (experience of the scientific school of professor P.V. Senin). (Materials and methods) Applied scientific and theoretical methods of analyzing the experience of the functioning of a scientific school, summarized and interpreted the criteria for its success as a form of personal growth and becoming a researcher at a university. Scientific and technical literature and publications in the field of humanitarian knowledge were used in the study. (Results and discussion) The experience of the P.V. Senin scientific school has shown that the implementation of the mechanisms of personal growth and formation of researchers at the university is the inclusion of students in the process of the scientific school, based on the creation of innovation centers, research laboratories, student teams, as well as the publication activity of the community of scientists on the basis of general theoretical and methodological approaches reflecting common research results. It was determined that the priority task of the scientific school is the interaction of university science and economic sectors aimed at creating technologies for high-resource repair of machines using the method of electric spark processing. (Conclusions) The results of the activities of the P.V. Senin scientific school allow us to consider this structure as a point of personal growth and professional development of a research student, a young scientist.

Comprehensive Proteome and Acetylome Analysis of Needle Senescence in Larix gmelinii.

Leaf senescence is essential for the growth and development of deciduous trees in the next season. Larix gmelinii, a deciduous coniferous tree, exhibits its most distinctive feature by turning yellow in the autumn and eventually shedding its leaves, resulting in significant changes in its appearance during the fall. Lysine acetylation plays an important role in diverse cellular processes; however, limited knowledge is available regarding acetylations in the needle senescence of L. gmelinii. In this study, the proteomics and acetylated modification omics of two phenotypic leaves, yellow and green (senescent and non-senescent) needles, were analyzed before autumn defoliation. In total, 5022 proteins and 4469 unique acetylation sites in 2414 lysine acylated proteins were identified, and this resulted in the discovery of 1335 differentially expressed proteins (DEPs) and 605 differentially expressed acetylated proteins (DAPs) in yellow versus green needles. There are significant differences between the proteome and acetylome; only 269 proteins were found to be DEP and DAP, of which 136 proteins were consistently expressed in both the DEP and DAP, 91 proteins were upregulated, and 45 proteins were down-regulated. The DEPs participate in the metabolism of starch and sucrose, while the DAPs are involved in glycolysis and the tricarboxylic acid cycle. Among them, DEPs underwent significant changes in glycolysis and citric acid cycling. Most of the enzymes involved in glycolysis and the citrate cycle were acetylated. DAPs were down-regulated in glycolysis and up-regulated in the citrate cycle. In all, the results of this study reveal the important role of lysine acetylation in the senescence of L. gmelinii needles and provide a new perspective for understanding the molecular mechanism of leaf senescence and tree seasonal growth.

Crack growth and fracture mechanics of CuCrFeNiCo high-entropy alloy during tension testing

Crack growth and fracture mechanics of CuCrFeNiCo high-entropy alloy during tension testing

Molecular Dynamics Simulation of Silicone Oil Polymerization from Combined QM/MM Modeling.

We outline a molecular simulation protocol for elucidating the formation of silicone oil from trimethlyl- and dimethlysilanediole precursor mixtures. While the fundamental condensation reactions are effectively described by quantum mechanical calculations, this is combined with molecular mechanics models in order to assess the extended relaxation processes. Within a small series of different precursor mixtures used as starting points, we demonstrate the evolution of the curing degree and heat formation in the course of polymer chain growth. Despite the increasing complexity of the amorphous agglomerate of polymer chains, our approach shows an appealing performance for tackling both elastic and viscous relaxation. Indeed, the finally obtained polymer systems feature 99% curing and thus offer realistic insights into the growth mechanisms of coexisting/competing polymer strands.

HGG-15. SYNERGISTIC EFFECTS OF COMBINED MEK/CDK4/6 INHIBITOR TREATMENT ON BRAFV600E POSITIVE HIGH-GRADE GLIOMA

Abstract BACKGROUND Pediatric high-grade glioma (pHGG) is associated with poor overall survival and standard care has remained unchanged for the past decade. BRAFV600E mutations occur in 5-10% and dabrafenib in combination with mekinist is approved in this subtype. Nevertheless, acquired resistance to targeted therapeutics is a common setback in highly aggressive tumors. Homozygous CDKN2A/B loss co-occurs in approximately 60% of this pHGG subtype. Taking advantage of those combined molecular alterations and exploiting acquired resistance mechanisms is of utmost importance to increase overall survival in these patients. METHODS Four HGG cell models with BRAFV600E mutation and homozygous CDKN2A/B loss were tested for the effects of CDK4/6 inhibitor monotherapy (palbociclib, ribociclib, abemaciclib) and/or combination treatment with trametinib on cell survival, cell cycle, apoptosis and senescence. RESULTS Abemaciclib showed the highest efficacy of CDK4/6 inhibitors comparable to trametinib monotherapy in our cell models. Abemaciclib led to a cell cycle arrest and combined treatment with trametinib induced distinctly increased levels of apoptosis in our tumor models when compared to monotherapy and a great proportion of surviving cells were senescent. One cell model was orthotopically implanted in mice and abemaciclib and combined treatment with trametinib showed a slightly increased response when compared to trametinib alone. CONCLUSIONS Summarizing, treatment with abemaciclib showed promising therapeutic effects in HGG cell models with BRAFV600E mutation and homozygous CDKN2A/B loss comparable to trametinib alone. Levels of apoptosis were distinctly higher with combinatorial abemaciclib and trametinib treatment when compared to monotherapy alone and senescence was induced in a great number of surviving cells. In vivo abemaciclib was more efficient when compared to trametinib alone. Currently we are working on in vivo experiments and the effect on sustained induction of senescence and mechanisms of tumor cell growth after discontinuation of therapy and in a combinatorial metronomic approach and in combination with radiotherapy.

Review of Anodic Tantalum Oxide Nanostructures: From Morphological Design to Emerging Applications.

Anodization of transition metals, particularly the valve metals (V, W, Ti, Ta, Hf, Nb, and Zr) and their alloys, has emerged as a powerful tool for controlling the morphology, purity, and thickness of oxide nanostructures. The present review is focused on the advances in the synthesis of micro/nanostructures of anodic tantalum oxides (ATO) in inorganic, organic, and mixed inorganic-organic type electrolytes with critically highlighting anodization parameters, such as applied voltage, current, time, and electrolyte temperature. Particularly, the growth of ATO nanostructures in fluoride containing electrolytes and their applications are briefly covered. The details of the current- or voltage-time transient and its relation to the growth of the anodic oxide films are presented systematically. The main discussion revolves around the incorporation of various electrolyte species into the surface of ATO structures and its effects on their physicochemical properties. The latest progress in understanding the growth mechanism of nanoporous/nanotubular ATO structures is outlined. Additionally, the impact of annealing temperature (ranging from 400-1000 °C) and atmosphere on the crystalline structure, morphology, impurity content, and physical properties of the ATOs is briefly described. The common modification methods, such as decorating with other transition metal/metal oxide, heteroatom doping, or generating defects in the ATO structures, are discussed. Besides, the review also covers the most promising applications of these materials in the fields of capacitors, supercapacitors, memristive devices, corrosion protection, photocatalysis, photoelectrochemical (PEC) water splitting, and biomaterials. Finally, future research directions for designing ATO-based nanomaterials and their utilities are indicated.

The physiological and biochemical role of silicon in enhancing the resistance of maize to root‐lesion nematode

AbstractSilicon (Si) plays an important role in enhancing the tolerance of plants to biotic and abiotic stress in soil ecosystems. Root‐lesion nematodes (Pratylenchus scribneri; RLNs) cause root damage and diseases that result in quality deterioration and economic loss. This study investigated the effects of Si application on maize plants and its interaction with RLN infection. We set up different treatments to evaluate the role of silicon application in maize root growth and RLN resistance. This study conducted analysis by combining measurements of the metabolism and root activity of maize under different conditions. The results suggested that Si application (0.5 g/kg) significantly promoted fresh shoot weight, plant height, SPAD value (chlorophyll content), and root activity of maize, regardless of RLN inoculation. The highest SPAD value was observed in the Si treatment, which was significantly higher than in the control (CK) and RLN (N) treatments. Analysis of enzyme activity revealed that nematode inoculation reduced catalase (CAT) activity and increased malondialdehyde (MDA) concentration, while Si application increased CAT activity and decreased MDA concentration. In the SiN treatment, there was increased CAT activity at 0, 12, 48, 72 and 96 h compared with the N treatment. In parallel, nematode inoculation increased phenylalanine ammonia‐lyase (PAL), and polyphenol oxidase (PPO) activities, while SiN treatment further enhanced their activities. These findings indicate that Si application enhances maize resistance to nematode infection and improves plant growth and antioxidant defence mechanisms.

Precise Regulation the Multiemission Based on Soft Double Salt for Information Encryption.

Manipulation of multiemissive luminophores is meaningful for exploring luminescent materials. Herein, we report a soft double salt assembly strategy that could result in well-organized nanostructures and different luminescence based on multiple weak intermolecular interactions thanks to the existence of electrostatic attraction between the anionic and cationic platinum(II) complexes. The cationic complexes B1 and B2 can coassemble with anionic complex A, respectively, and the emission switches from monomeric and excimeric emission to the triplet metal-metal-to-ligand charge transfer (3MMLCT) along with morphology changes from 0-dimensional (0-D) nanospheres to 3-dimensional (3-D) nanostructures. It is demonstrated that an isodesmic growth mechanism is adopted during the spontaneous self-assembly process, and the relative negative ΔG values make the anionic and cationic complex molecules prefer to form aggregates based on π-π stacking, Pt···Pt interactions, and electrostatic interactions. The coassembly strategy between anionic and cationic complexes endows them with multicolor luminescent and apparent color as optical materials for advanced information encryption.

Effect of Ge inclusion on surface morphologies and the growth mechanism of Cu2(Sn1-xGex)S3 films grown by the sulfurization of Ge/Cu/SnS precursors

The effects of the [Ge]/([Ge]+[Sn]): x ratio on the increase in the surface roughness and growth mechanism of Cu2Sn1-xGexS3 (CTGS) films were examined as a first step toward realizing high-efficiency CTGS solar cells. The surface roughness of the CTGS films did not change significantly up to 450 °C during the sulfurization of the Ge/Cu/SnS precursors, whereas that of the CTGS films increased beyond 500 °C. Further, Cu2GeS3 (CGS) and germanium sulfide (GeS) were observed via X-ray diffraction; these CGS and GeS compounds remained in the upper layer up to 540 °C, and CTGS was formed at 560 °C by the reaction with Cu2SnS3. The increased surface roughness in the CTGS films is attributed to the larger CTGS grain size that increases the x ratios of CTGS and the re-evaporation of vapor atoms (e.g., GeS) that generates a high vapor pressure on the surface of films by forming CGS and GeS compounds. These results confirm that the formation of CGS and GeS compounds, and the formation of dense grains in the CTGS films caused by the deposition of lower x ratios in the CTGS films are effective measures for improving the overall surface roughness.

Synthesis of Silver Nanostructures on Different Supports: From Nanoparticle Decoration to a Complete Shell Growth

AbstractIn this work, we investigate a complete strategy to obtain supported silver nanostructures (AgNSs) which can be used for different applications such as catalysis, optoelectronics, and biomedical devices. Given the poor wetting of silver on many support materials, the anchorage of silver nanoparticles (AgNPs) to the substrate (decoration) is achieved by employing an oxide precipitation‐decomposition method. This protocol is optimized to obtain rapid and homogeneous decoration of AgNPs on different substrates such as silica, titania, and hydroxyapatite with a negligible production of free‐standing silver nanoparticles. Going a step further, we have also studied the growth of AgNPs attached to silica spheres (SiO2NPs) using a seed‐mediated growth strategy. The interplay of different processes like growth, corrosion, coalescence, and sintering determines the morphological features of the grown nanoparticles. Therefore, the substrate coverage and nanoparticle morphology can be qualitatively modified by varying the composition of the growth bath. The observed growth is consistent with a radial growth mechanism which, in most experimental conditions, allows for the production of anisotropic AgNSs onto silica surface. In addition, if the corrosion effects are minimized, the coalescence process of neighboring particles can lead to high surface coverages.

Physical networks as network-of-networks

Physical networks are made of nodes and links that are physical objects embedded in a geometric space. Understanding how the mutual volume exclusion between these elements affects the structure and function of physical networks calls for a suitable generalization of network theory. Here, we introduce a network-of-networks framework where we describe the shape of each extended physical node as a network embedded in space and these networks are bound together by physical links. Relying on this representation, we introduce a minimal model of network growth and we show for a general class of physical networks that volume exclusion induces heterogeneity in both node volume and degree, with the two becoming correlated. These emergent properties strongly affect the dynamics on physical networks: by calculating their Laplacian spectrum as a function of the coupling strength between the nodes we show that degree-volume correlations suppress the role of hubs as early spreaders in diffusive dynamics. We apply the network-of-networks framework to describe several real systems and find properties analog to the minimal model networks. The prevalence of these properties points towards general growth mechanisms that do not depend on the specifics of the systems.

Electrochemical deposition and characterization of cuprous oxide crystallites on stainless substrates: Growth mechanism and morphological analysis

In this article, we present the growth process of cuprous oxide (Cu2O) crystallites on the stainless substrates from an aqueous cupric acetic solution under electrochemical deposition method. Copper acetate (Cu(Ac)2) aqueous solution was used as the electrolyte with the applied potential and reaction time for electrodeposition were varied in this study. Pure Cu2O crystallites of cubic phase with specific surface morphologies were observed under electrodeposited at certain temperature. The specific shape of crystallites electrodeposited at 25 °C is the structure with four identical pyramid-shaped leaves pointing outward and a pointing upward stamen in the middle. The crystal growth type can be classified as the branching growth through a surface diffusion mechanism based on the growth exponent (L ∝ t1/2). The growth of Cu2O crystal is suggested to be surface diffusion of adatoms in dendrite branching growth. A mechanism for the growth of Cu2O crystals under electrodeposition was proposed based on the XPS results. As the temperature increases, the morphology of Cu2O crystals under electrodeposition becomes thinner, but the shape does not change a lot.

Zinc and nitrogen mediate the regulation of growth, leading to the upregulation of antioxidant aptitude, physio-biochemical traits, and yield in wheat plants

An ample amount of water and soil nutrients is required for economic wheat production to meet the current food demands. Nitrogen (N) and zinc (Zn) fertigation in soils can produce a substantial wheat yield for a rapidly increasing population and bring a limelight to researchers. The present study was designed to ascertain N and Zn’s synergistic role in wheat growth, yield, and physio-biochemical traits. A pot experiment was laid out under a complete randomized design with four N levels (N1-0, N2-60, N3- 120, and N4-180 kg ha−1), Zn (T1-0, T2-5, T3-10, and T4-15 kg ha−1) with four replications. After the emergence of the plants, N and Zn fertigation was applied in the soil. The growth traits were considerably increased by combined applications as compared to the sole applications of the N and Zn. The photosynthetic pigments were found maximum due to combined applications of N and Zn, which were positively associated with biomass, growth, yield, and wheat grain quality. The combined application also substantially enhances the antioxidant enzyme activities to scavenge the ROS as H2O2 and reduce lipid peroxidation to protect the permeability of the biologic membranes. The combined higher applications of N and Zn were more responsive to ionic balance in a shoot by maintaining the Na+ for osmotic adjustments, accumulating more Ca2+ for cellular signaling; but, combined applications resulted in K+ reduction. Our present results suggest that appropriate sole or combined applications of N and Zn improve wheat's growth, yield, and antioxidant mechanisms. Previous studies lack sufficient information on N and Zn combined fertigation. We intend to investigate both the sole and combined roles of N and Zn to exploit their potential synergistic effects on wheat.

Small‐Molecule Fluorescent Probes for Plant Hormones and their Receptors

AbstractPlant hormones and their receptors play a crucial role in regulating plant growth and adapting to the stress environment. The exploration of interaction between plant hormones and their receptors is significant to comprehend the molecular mechanisms of plant growth and development, the response mechanisms of adaptation to environmental changes, and to optimize the traits and stress‐resistance of crops. Since the biosynthesis, transport, and metabolism of hormones in plants are closely relevant to spatio‐temporal changes, and their content and distribution are highly dynamic, there is an urgent need for a qualitative and quantitative tool to accurately, real‐time, and in situ monitor the dynamic changes of hormones in plants without injury. Fluorescent probes have been widely used in the sensing and imaging of plant hormones and their receptors, due to their high spatio‐temporal resolution, high selectivity, non‐invasive, high sensitivity, and tailored molecular structures. Here, this paper provides a systematical overview of the research progress in the sensing and imaging of plant hormones and their receptors using fluorescent probes. In addition, the potential prospects and remaining challenges are also discussed to design fluorescent probes with better performance and promote the development of this field.

Improving the Magnetic Properties of Electrodeposited Fe-55wt%Ni Alloy via Abnormal Grain Growth Induced by Second-Phase Particles

In this study, pulse reverse current electrodeposition was employed to fabricate Fe-55 wt%Ni alloy. Abnormal grain growth induced by the precipitation of second-phase particles during annealing resulted in a coarse-grained electrodeposited Fe-55 wt%Ni alloy. The grain evolution process during annealing was investigated, and the temperature for abnormal grain growth was determined through the high-temperature confocal microscopy technique. Subsequently, the mechanism of abnormal grain growth was investigated. The results suggest that abnormal grain growth occurs at approximately 1003 K, attributed to the preferential growth of (110) oriented grains due to local strain energy changes caused by the precipitation and coarsening of the second-phase particles (MnS). The preferred orientation of the grains transitioned from (111) to (110). Annealing at 1073 K for 2 h resulted in an average grain size increase to approximately 200 μm. Under these conditions, the magnetic properties of the alloy reached optimal levels, with a magnetization saturation strength of 186.7 emu g−1 and a coercivity of less than 1 Oe. This research presents a novel approach to preparing coarse-grained electrodeposited Fe-Ni alloys, significantly enhancing their magnetic properties.

Low-defect and stress-free AlN(0001) nanoprisms and microrods selectively grown on micro-patterned c-sapphire substrate by plasma-assisted molecular beam epitaxy

This paper describes different growth modes of AlN layers on micro-cone patterned c-sapphire substrates (μ-PSSs) using plasma-assisted molecular beam epitaxy. Ordered arrays of AlN nanoprisms and microrods were selectively grown on the tips of μ-PSS's microcones according to a bottom-up formation mechanism using sequential migration enhanced and metal-modulated epitaxy (MME) under metal-rich growth conditions at 820 °C. Transmission electron microscopy revealed structurally perfect AlN regions above the tips of the μ-PSSs, which initiate as inverted nanopyramids with {1011¯} side faces, evolving into hexagonal nanoprisms with orientations of {11¯00} and (0001) for side and top surfaces, respectively. The diameter and height of these ordered hexagonal nanoprisms, which have a 60% probability of nucleating, were about 1 μm. Long-term MME growth of these nanoprisms in both vertical and lateral directions led to the formation of AlN(0001) microrods with a maximum possible diameter of two micrometers and a height of up to 6 μm. Atomic force microscopy revealed a mixed step-flow and 2D nucleation growth mechanism for the flat tops of these AlN nanoprisms and microrods with an average surface roughness of 1–2 monolayers. Micro-Raman spectroscopy demonstrated narrow E2 (high) linewidths of 3.8 and 4.2 cm−1 for essentially stress-free AlN nanoprisms and microrods, respectively.

Preparation and growth mechanism of nonpolar, semipolar and polar ZnO films: Correlation of preferred orientation, defects and optical properties

In the study, ZnO films with different preferred orientations were controllably prepared by using NH3·H2O to modulate the pH0 of chemical bath deposition. The samples were all characterised by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray diffraction (XRD), ultraviolet-visible spectrophotometry (UV–VIS), X-ray photoemission spectroscopy (XPS) and photoluminescence (PL). The results show that ZnO films with polar, semipolar and nonpolar preferred orientations can be synthesised in a controlled manner by varying the pH0. Meanwhile, the influence of NH3·H2O concentration on the growth process of ZnO films is investigated in detail, and the relationship between the preferred orientation and optical properties is preliminarily discussed. At pH0= 7.32, the films exhibited semipolar (101) preferred orientation, the highest optical transmittance (89.15 %), and the highest concentration of Zni in the films. This study provides a method for the controlled synthesis of ZnO films with polar, semipolar and nonpolar preferred orientations and offers new possibilities for ZnO-based transparent semiconductor devices.